Endurance Sports Nutrition: Everything You Need to Know!

Isabel del Barrio 9 min. of reading Running Leave a comment

An important aspect that every athlete should be aware of is nutrition for endurance sports.

Endurance sports are in full growth with more and more amateur runners and athletes moving to medium, long and ultra-distance events.

Whether they have extensive previous training or, on the contrary, lack experience, it’s clear that, in addition to the need for an individualised training plan to achieve the objectives set, the need for a nutrition and supplementation plan also becomes a necessary requirement to successfully achieve them.

Index

1 Determining factors for performance
2 The Importance of Nutrition
3 Energy Production Systems
4 Athlete Condition
5 How Do Carbohydrates Work during exertion?
6 What happens in intense, long-duration activities?
7 Do we have to pay attention to the GI?
8 How do fats work during exercise?
9 Energy Substrate Predominance according exercise intensity
10 What is the main energy substrate in a marathon?
11 What other factors play a role when exercising?
12 Bibliographical References
13 Related Entries

Determining factors for performance

Nutrition and rest go hand in hand with training plans and play a fundamental role in improving performance and adapting to loads, training volumes and recovery.

However, many endurance athletes leave these issues to one side in order to keep adding kilometres to their volume.

But when we subject the body to high doses of mechanical and psychological stress, along with demanding… as if it were a car engine, it suffers significant wear and rust.

On the other hand, the endurance sport is in itself oxidative, and therefore requires recovery mechanisms.

Athletes need to understand that, as training intensities and volumes increase, for the necessary adaptations to take place, their bodies need to function well and perform optimally,

“The combination of rest + nutrition + supplementation (in each individual case) are your main allies.”

In the following articles, we’ll focus specifically on what Nutrition / Supplementation in endurance races should be like:

Medium and Marathon
Medium and Ironman
Ultra-Distance Running.

Although it may seem obvious, each one must take into account specific characteristics depending on the particular competition, in addition to certain common factors.

The Importance of Nutrition

Nutrition is one of the axes on which the training process for endurance sports should revolve.

Not only to optimise performance and recovery, but also to ensure a good state of health and well-being.

Foods for endurance sports

In this article, we’ll cover the general outlines of tests and/or workouts lasting more than 60 minutes.

Energy Production Systems

When talking about nutrition and the periodisation of nutrition in endurance sports, the first thing to consider is the main energy/metabolic pathways or systems in each specific sport.

The different energy systems (alactic anaerobic, lactic anaerobic and aerobic) do not act independently — each works and contributes to the total energy needs of the body.

As such, you need to determine the exercise intensity and duration in order to know which energy substrate or metabolic pathway is predominant and plan intake and nutrition from there.

Runners

What we need to know in each case is which of them is predominant and what the dynamics of each type of substrate are in each type of exercise or activity.

Likewise, the periodisation of nutrition and supplementation throughout the season (taking into account the training cycles, intensities, volumes, and what you want to work on and enhance in each of them).

If you want to learn more about Energy Systems, check out this link.

Athlete Condition

In addition to intensity and duration, the physical form and nutritional status of the individual are also determining factors.

Although we know that at moderate intensities the predominant metabolic pathway is aerobic (fat oxidation), characteristic of long-duration exercise in which a certain intensity must be maintained, this doesn’t imply glycogen substrates don’t participate, but they do so in a lower percentage.

Athlete Objectives

Endurance athletes should therefore aim to work on the body to make it more energy efficient and more dependent on fats.

Without forgetting that carbohydrates will also play an important role as the duration and intensity of the training / test increase.

How Do Carbohydrates Work during exertion?

Muscle glycogen (from Carbohydrates) is the main source of energy in the initial phases of exercise:

At the beginning (the first 10-20 minutes) of the activity, there’s a peak or an increase in the rate of use of carbs.

When does muscle glycogen become depleted?

As we said before, it will depend on:

The starting point and nutritional status of the individual;
And the intensity of the effort.

Depletion occurs when the body requires the glycolytic pathway as the main metabolic pathway in prolonged and intense efforts (approximately 85% VO2 max).

Hence the need for supplementation during workouts / tests of more than 60 minutes in duration at moderate to high intensities.

Marathon runners.

What happens in intense, long-duration activities?

In activities that last up to 2-3 hours, trying to maintain a demanding intensity, energy comes from aerobic glycolysis, together with fatty acids, reaching a point where muscle glycogen stores are depleted.

Blood glucose becomes a major substrate in these carbohydrate metabolism conditions.

This is the fundamental reason nutritional strategies and their planning must be incorporated into programmes to also avoid states of hypoglycaemia and fatigue.

Do we have to pay attention to the GI?

The glycaemic index of carbohydrates is also relevant when designing the different nutritional strategies (before, during and after training / testing).

The following is recommended:

Low glycaemic index for intake before training / testing.
High glycaemic index for intake during training, due to rapid availability and absorption.

The availability of carbohydrates will also determine their use for energy supply.

Intense exercise

A neurohormonal response is triggered: release of adrenaline, noradrenaline and glucagon, and a drop in insulin. The main energy substrate is muscle glycogen in the initial minutes.

As time goes by, blood glucose increases its contribution to energy intake, providing up to 30% of energy needs.

Moderate Intensity Long-Duration Exercise

At lower exercise intensity (predominance of type I slow fibres), the main energy substrate is fat.

Carbs are also used as a metabolic pathway: they’ll come from stored glycogen, and circulating glycogen.

How do fats work during exercise?

Oxidation of fatty acids depends on:

The availability of FFL, which at the same time, is determined by the mobilisation of these FFL; and
The body’s capacity to oxidise these fatty acids.

Hence the importance of training this energy efficiency and endurance athletes teaching their bodies not to be so dependent on carbs.

Fat provides between 30% – 80% of energy for physical activity, in addition to the physical condition of the individual / athlete.

Salmon: an important source of fat and omega-3. Discover the benefits of these essential fatty acids here.

Energy Substrate Predominance according exercise intensity

At low-intensity

It increases the blood flow in the adipose tissue, promoting the mobilisation of these fatty acids so that they can be used as an energy substrate.

Sympathetic activation as well as decreased insulin levels promote this mobilisation of fatty acids from adipose tissue.

At low-moderate intensity

Both carbohydrates and triglycerides provide energy almost equally, increasing the use of fatty acids as the duration of activity increases, and as glycogen deposits are depleted.

Training would promote the use of fats as the main energy substrate and a “saving” (efficiency) in the use of Carbohydrates.

This would be so that, at the same relative intensity, the body learns to obtain the greatest energy contribution from fats, and less from carbs.

This is one of the reasons that justify some athletes training while fasting during certain periods of the season, continue reading....

What is the main energy substrate in a marathon?

As we’ve seen, the intensity of exercise and its duration are the key factors when determining the predominance of an energy substrate.

Knowing that a marathon for an amateur athlete is demanding for a duration of 2.5 – 4 hours, and that the intensity of the exercise is moderate and close to the first ventilatory threshold, the main substrate will be fats.

But as we’ve seen, as the duration increases, the glycogen deposits are also being depleted, and these will need to be replaced intermittently.

Adaptation to training

We should bear in mind that, in trained individuals / athletes, the objective is to seek an adaptation of the body to a greater use of fatty acids, which are more efficient and economical in the use of carbohydrates (which we know are used up first).

What other factors play a role when exercising?

Of course, it will depend on the nutritional status of the individual prior to exercise.

The concentrations of each substrate will determine the use of one or the other during the activity (hence the importance of periodisation of nutrition and supplementation during the season and prior to competitions).

Also directly affecting the planning of the nutrition / hydration strategy during the race are environmental and temperature factors.

In the following articles, we’ll focus on nutritional / supplementation recommendations for each type of event specifically.

Bibliographical References

Cardona C, Cejuela A, Esteve J. Manual para Deportes de Resistencia. All in Your Mind Training System. (2019).
Jeukendrup A, Gleeson M. Nutrición Deportiva. Ediciones Tutor (2019).
López Chicharro J, Fernández Vaquero A. Bioenergética de las células musculares. Ed. Exercise Physiology and Training. (2017).

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